Party-line telephone system.



W. W. DEAN.

PARTY LINE TELEPHONE SYSTEM.

APPLIOATION FILED MAY 4, 1914.

Patented Dec. 8, 1914.

n5 NORRI; PETERS C0 PHOTO-LITHQ. WASHING roN. n r

UNITED STATES PATENT OFFICE- WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE GARFORD MANUFAC- TUBING COMPANY, OF EL YRIA, 01-110, A CORPORATION OF OHIO.

Specification of Letters Patent.

Original application filed March 12, 1908, Serial No. 420,546. Divided and this application filed May 4,

1914. Serial No. 836,106.

T 0 all whom it may concern:

Be it known that I, VILLIAM W. DEAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and Improved Party-Line Telephone System, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

This application is a division of my application No. 420,546, filed March 12, 1908.

WVith the advent of high voltage currents for signaling on party-lines, there has arisen a'danger of injuring the ear of a waiting subscriber when the operator inadvertently or otherwise rings upon a busy line.

One of the objects of my invention is to make it impossible for the operator to ring upon a busy line.

Some of the telephone systems which have been used in the past have been provided with a plurality of contact carrying springs connected in series in a talking circuit, and so arranged that when any set of springs is operated, the contacts thereof are separated from that portion of the cord circuit. The same operation connects the spring with one of a plurality of sources of ringing currents and thence by means of ringing conductors and the plug and jack to the called party-line. The presence of a plurality of contacts in the talking circuit is objectionable for several reasons. The contacts in the talking circuit should be of platinum which is very expensive, whereas, those in the ringing circuit should be of a cheaper material. Each contact ofiers a certain amount of resistance to the flow of talking currents, especially when it becomes dirty or corroded.

Another object of my invention is to provide a circuit wherein these contacts are eliminated from the talking circuit.

Other objects of my invention and the invention itself will probably be better understood from a description of an embodiment of my invention.

The figure is a diagrammatic representation of an embodiment of my invention.

Referring now to the drawings, I have shown two party lines extending by their limbs 1, 2 and 3, 4 from a plurality of substations, A, A, A A and C, C,-C C to when attracted to close the contact 67 and thus to complete a circuit between wires 50 and 51 and through line lamp 68. Armatures 56 and 57 are adapted to be operated by relay B, one terminal of which is connected by a wire 69 with the rings 60 and 61 of jacks J and J, while the other terminal of the winding of this relay R is connected by wire 51 with the grounded terminal of battery The substation A is equipped with the transmitter 13 connected through the usual hook switch with the line wire 1, and with the terminal of this transmitter is connected the juncture of windings 14 and 16, which are two windings of a VVheatstone bridge arrangement used for supplying current to the receiver 18. This Wheatstone bridge consists of the inductive windings 16 and 17, and the non-inductive windings 14 and 15 so connected and of such resistance that the receiver 18 is connected in bridge between the points of juncture of the windings 15 and 16 and 14 and 17, which points are of equal potential when direct current Patented Dec. 8, 1914.

flows from the transmitter 13 through these 7 connected windings and back to line wire 2.

As a result of the impedance value of the windings 16 and 17, however, when voice currents flow through this same circuit they are practically all directed through the receiver 18. A ringer 12 in circuit with condenser 11 is also provided in bridge of the line wires 1 and 2. I have illustrated this form of substation circuit, though my invention is not limited thereto, any suitable form of substation circuit being contemplated.

As a result of the construction described above, when the receiver is removed from the switch hook at the substation A, the relay R is energized, current taking the following path: battery B, wire 50, relay R, contact 53, armature 56, wire 1, transmitter 13, thence through the bridge windings back to wire 2, armature 57, contact 59, wire 51, to battery B, as a result of which the relay R is energized and a circuit closed through the line lamp 68 as follows: battery B,wire 50, armature 66, contact 67, lamp 68, wire 51 back to the battery B. In response to this signal and answering plug of the cord pair is inserted inv the answering 3ack with the result that precisely the same operation takes place as illustrated for the calling plug P, which is as follows: the sleeve relay S connected with the plug is energized by the following circuit: battery B, wire 50, wire 43, wire 45, relay S, wire 44, cord strand 6, sleeve 63 of the plug P, ring 60, wire 69, relay R, wire 51, back to battery B. As a result of this the relay R is energized and armatures 56 and 5'7 are removed from contacts 58 and 59, respectively, cutting off connection between the battery B and the line wire 1 and 2.

The several ringers located at the different substations may be of any well known type adaptive to selective signaling, that form of ringer known as the harmonic ringer being particularly available for this purpose, and the first named object of my invention being especially realized in connection with this type of ringer where high voltage frequencies are frequently used.

' The cord circuit shown for connecting lines for conversation consist of tip and sleeve strands 5, 7,, .9and 6, 8, 10, respectively, terminating in answering and calling plugs P and P. Strands 5, 6 terminate in tip and sleeve 62 and 63, respectively, of calling plug P, while the strands 9, 10 terminatesimilarly at the answering plug P Besides the relay S associated with the sleeve strand as above described, there is a second relay T associated with the tip strand, the two relays coiiperati'ng to effect the supervisory signaling for the calling plug. Simi lar relays are associated with the tip and sleeve strands of the answering plug, but

I since the supervision of the connection is not a feature of this invention, no reference is made to the signaling relays except in so far as they are concernedin this control of the circuits forming the subject-matter of this invention.

When the relay S is energized as described above, by the plug P being inserted into the jack J, a'signaling circuit'is closedas fol- I lows: battery B, wire, 50, wire 43, wire 45,

contact 35,'armature 34, wire 48, contact 37, armature 36, supervisorylamp 38, wire 41, wire 42, back to battery B. The relay S also closes a second circuit as follows: from the tip strand 7, through wire 39, armature 32, contact 33, relay T, wire 41, wire 42 to the grounded terminal of battery B, as'a result of which when the line wire 2, which is at this time connected to the cord strand 7, is connected with the live side of the battery, the switch T will be energized. This is accomplished when the receiver is 're moved from the switch hook at one of the substations, current taking the following path: batery B, wire 50, wire 43, wire 45, relay S, wire 44, cord strand 6, sleeve 63, contact spring 53, line wire 1, transmitter 13, line wire 2, jack spring 52,,tip 62, cord strand 5, key spring contact 25, cord strand 7 wire 39, armature32, contact 33, wire 40, relay T, wire 41, wire 42, back to battery B. This attracts armatures 36 and 29, breaking the supervisory circuit and also breaking a second circuit which was closed between the armature 29 and contact 31. This circuit was effective before the subscriber answered in sending signal current i on to the line as follows: The ringin'g'keys Z0, is, 70 k are connected through their noranally open contacts 21, 22, 23- and 24 with the ringing generators G, G, G G adapted to selectively ring the several substations connected to the di'fierent lines. The ringing keyslc, k, 71: is? are mechanically connected by means not shown -with the key springs 70* and 10 so that when operated to put ringing current on tothe line the cord strands are opened to prevent the ringing current flowing back into the-answering end of the cord. Assu'n'iing that current from the generator G is adapte'dto' operate the ringer 12, the ringing key 70 is. operated,

and if the receiver 18 has not been removed from the switch hook a 'circuit would be completed as follows: ringing generator G, contact 22, spring is", wire '20, contact 31, armature'29, wire 49, cord strand 5, tip 62, jackspring 52,-line wire 2, condenser 11,

ringer 12, line wire 1, ack spring 53, sleeve 63, ring 60, wire 69, relay It, wire 51, ground g, groundv 9- back to generator G. From the circuitjust traced it appears that when relay T is energized the connection of the ringing generator to the cord circuit is interrupted and that the operation of the keys 7a, 70', is, 70 will not produce any effect upon the cord circuit orthe line with which the cord circuit may'beconnected. When the gages contact 30, establishing aconnection between the cord strands 5 and 7 whichvconnection efiects the holding of the relay Tiif one of the ringing keys is energized, while i the line connected with the calling plug is busy. This circuit is traced as follows: battery B, wire 50, wire 43, wire 45, relay S, wire 44, sleeve strand 6, sleeve 63, jack spring 53, line wire 1,ztrans'iiiitter 13, line wire 2', jack spring 5 2, tip 62, tip strand 5, wire 49, armature 29, contact 30, wire 70, cord strand 7 wire 39,- armature 32, contact 33, wire 40, relay T,wire 41, Wire 42, back to battery B.

2 1 15 relay T is'energized, the armature 29en- In the drawings the apparatus is indicated in the position which it would assume if the substation C were connected by means of the upper cord circuit with the substation A and both parties were engaged in conversation. A second cord circuit is shown in the lower part of the drawing which is a duplicate of the upper cord circuit in all respects, and this cord circuit is represented as connected with the line 1, 2, which as described above, is represented as busy. Whether the answering plug 39 of the lower cord circuit is in an answering jack of some other line, or whether it is entirely disconnected is immaterial to the operation of the relay T which is immediately energized upon the insertion of the plug P into the jack J connected with the busy line 1, 2. This energizing circuit may be traced as follows: battery B, wire 50, wire L5", relay 8*, wire 4%, cord circuit 6, sleeve 65, jack spring 55, line wire 1, transmitter 13, line wire 2, ack spring 5i, tip 6 1, cord strand 5*, key spring is, contact 25, cord strand 7 wire 39*, armature 32, contact 33 wire 40, relay T wire 41 wire 12 back to battery B.

After being energized, the relay T is held against release by the opening of the key is by means of a circuit as already described, which is identical with that shown for the cord circuit in the upper part of the drawing. The ringing key is shown as operated in the lower cord circuit, but as a result of the operation of the armature 29 the circuit is interrupted between armature 29 and contact 31 and hence connection between the generator G and tip 64 is interrupted and ringing current cannot be sent from the generator G to any of the substations connected with the line 1, 2. Since keys 7c, 7s, 10 It are all connected through the same circuit by wire 20 to the tip 64, it

will be understood that the operation of the relay T serves in similar manner to efi'ectually disconnect all of the ringing generators from the calling plug. By this means I have made it impossible for an operator to send ringing current out on a busy line and I have thus made it impossible to send ringing current through the receiver at any of the substations where such receiver is being used, and I have removed the ringing spring contacts from the talking circuit.

My invention is especially advantageous when used with party-line systems, because of the greater possibility of there being a subscriber on a -called line, owing to the fact that there are a plurality of substations on that line, and because with party lines a plurality of generators and consequently a plurality of ringing contacts are employed.

lVhile I have shown my invention in the particular embodiment herein disclosed, I do not limit myself to this modlficatlon, but claim broadly any equivalent construction for securing the same or any of theresults named.

I claim 1. Ina party line telephone system, the combination of a telephone line, a plurality of substations on said line, a cord circuit, a plurality of ringing keys for the cord circuit, a plurality of sources of signaling current, a supervisory relay, said ringing keys being connected with a strand of the cord circuit through normal contacts of said supervisory relay.

2. In a party line telephone system, the combination with a telephone line, a plurality of substations on said line, a cord circuit, a plurality of sources of signaling current, a plurality of ringing keys for the cord circuit each having a plurality of contacts normally in series with a portion of the talking strand of the cord circuit, a supervisory relay having contacts in the circuit of said keys, said relay being actuated (lur ing conversation to disconnect said series key contacts from the talking circuit, substantially as described.

3. In a party line telephone system, the combination with a telephone line, a plurality of substations on said line, a cord circuit, a plurality of ringing generators, a supervisory relay, the current from any of said generators being connected with the calling end of the cord circuit through normally closed contacts of said relay, substantially as described.

4. In a telephone system, the combination of a main station, a cord circuit thereat, a plurality of telephone lines extending by their limbs from the main station to the substations, a plurality of substations on one of said lines, ringers at the substations, a plurality of ringing generators associated with the cord circuit at the main station for operating the ringers at the substations, a supervisory relay and means including a plurality of ringing keys and normally closed contacts of said supervisory relay for connecting said sources of ringing current to the cord circuit.

5. In a party line telephone system, the combination with a main station and a cord circuit thereat, of a plurality of substations, telephone lines connecting the substations to the main station, one of said lines having a plurality of substations thereon, each of said plurality of substations being provided with a telephone ringer and substation set, a plurality of sources of ringing current associated with the cord circuit at the main station for operating the telephone ringers at the substations, a plurality of ringing keys controlling the connection of the sources of signaling current to the telephone lines, a supervisory relay associated with the cord circuit, and means including normal contacts of said supervisory relay for connecting the ringing keys with a strand of the cord circuit.

6. In a party line telephone system, the combination of la main station and a cord circuit thereat, a plurality of substations, telephone lines connecting the substations with the main station, one of said lines having a plurality of substations thereon, a telephoneringer and a talking set at each substation, means for connecting the cord circuit and the telephone lines together, said cord circuit being provided with a plurality of strands, a supervisory relay associated with the cord circuit, a plurality of sources of signaling current for operating the ringers at the substations,ringing keys controlling the connection, of the sources of signaling current to the cord circuit, the conta'cts of said keys being normally out of the path of the talking circuit, and means including a conductor and normal contacts of said supervisory relay for connecting any one of said ringing keys to a talking strand.

7 In a party line telephone system, the combination with a main station and a plurality of substations, of a called line leading from a plurality of substations tothe main station and terminating thereat, a switchboard jack at the main station in which said called line terminates, a ringer and a talking set at each of the substations on the called line, a calling line leading from a substation to the main station, a switchboard jack in which said calling line terminates, a cord circuit at the main station terminating in plugs adapted to be inserted in said switchboard jacks to .connect said calling and called lines together, a supervisory relay in the calling end of the cord circuit, a circuit for said supervisory relay including contacts of the calling plug and the switchboard jack of the called line, a source of di-- rect current for energizing said supervisory relay, a plurality of sources of signaling current at the main stationadapted to actuate the ringers at the substations, a ringing key for each source of signaling current controlling the connection of the same to the called line and means to connect said ringing keys to the cordcircuit including a conductor and normal contacts of said supervisory relay, said relay being actuated during conversation to disconnect said key contacts from the talking circuit, substantially as described.

8. In a party line telephone system, the combination of a main station and a plurality of substations, a calling line including a substation terminating at the main station, a switchboard jack in which said calling line terminates at the main station, a called line having a plurality of substations on said line leading to the main station, a switchboard jack at the main station in which said called line terminates, a ringer cord circuit and contacts of the calling plug and jack of the called line, a source of talking current included in the circuit of the supervisory relay, a plurality of sources of signaling current associated with the cord circuit at the main station for selectively operating the ringers at the substations, a plurality of ringing keys, oneassociated with each of the sources of signaling current and controlling the connection of the same to the called line, and means to connect said ringing keys toa talking strand of the cord circuit including a conductor and contacts of said supervisory relay, said supervisory relay being actuated: during conversation to disconnect the contacts of said keys from the'talking' circuit.

-9. In a party'line telephone system, the

combination of amain station and a plurality of substations, switchboard jacks at the main station, conductors connecting said substations with the switchboard jacks constituting a called and calling line, said called line having, a plurality of substaa ringer normally bridged across the line I and a talking set normally in an open bridge the cord circuit, a circuit for one ofthe sutions thereon and each substation including i pervisory relays in the calling end of the cord including the source of talking current, a portion or" the talking strand of the cord and contacts of the calling plug ofthe cord and the switchboard jack of the called line, a plurality of ringing genera-tors adapted when connected to the called line to supply current to selectively operate the ringers at the substations thereon, a plurality of ringing keys controlling ,the connection of the ringing generators to the called line, and a conductor and contactsof said last named supervisory relay controlling the connection of said ringing key to a talking strand of the cord circuit, said last named supervisory relay being actuated during conversation to disconnect said key contacts from the talking circuit, substantially as described.

10. In a party line telephone system, the combination of a main station and a plurality of substations, switchboard jacks at the main station, a telephone line leading from a plurality of substations to a jack at the main station and constituting a called line, the substations on the called line including a ringer normally in bridge of the line and a talking set in normal open bridge of the line, said normally open bridge being closed when the substation set is in use, a cord circuit at the main station including a pair of talking strands, plugs in which the talking strands are terminated adapted to be inserted into the jacks of telephone lines to connect the same together, a source of talking current at the main station associated with the cord circuit, a supervisory relay at the main station associated with the cord circuit, a circuit for said relay including said source of currents, a portion of a talking strand, contacts of one of the plugs of the cord circuit and the jack of the called line, the limbs of the called line and any one of the talking set bridges at the sub stations on the called line, a plurality of ringing generators at the main station associated with the cord circuit and adapted when connected to the called line to selec' tively operate the ringers at the substations, a plurality of ringing keys at the main station associated with the cord circuit and controlling the connection of the ringing generators to the called line, each key controlling one of said generators, means for connecting the contacts of the ringing keys with the calling plug including a portion of a talking strand of the cord strand, a conductor and normally closed contacts of said supervisory relay, said relay being actuated during conversation to disconnect said key contacts from the talking circuit.

In testimony whereof I have aflixed my signature in the presence of two witnesses, this 21st day of April, 1914.

WILLIAM w. DEAN.

l/Vitnesses:

FRANK M. SLOUGH, C. B. HARLOW.

Copies of thiapatent may be obtained for five cents each, by addressing the commissioner of latenta.

Washington, D. G." 

